Three things that have no business being in the same sentence. A physics trick from 1949. A fake name from a Bollywood film about engineering college trauma. An algorithm running on every GPU cluster on Earth.

And yet.

I was debugging a neural network at 2 AM. Loss function stuck, gradients vanishing, the usual. I gave up and put on 3 Idiots for the twentieth time. Comfort viewing. Rancho was explaining how fear makes you stupid, and I was half-watching, half-thinking about why my model wouldn’t learn, when he said something about the heart being easily fooled, tell it “aal izz well.”

Then it hit me. The model learns backward. Rancho lives backward. And somewhere in a Feynman diagram, an electron is doing exactly the same thing.

What if the direction we call “forward” is the problem?

Richard Feynman had this idea that sounded insane. A positron, the antimatter twin of an electron, is just a regular electron traveling backward through time. When matter and antimatter annihilate, Feynman saw one electron bouncing off the present like a wall, reversing direction, heading back the way it came.

The math checks out. The equations of physics work the same in both directions. Play any fundamental interaction in reverse and it still holds. The arrow of time we feel, yesterday gone, tomorrow coming, that’s just statistics. Entropy. The improbability of spilled milk jumping back into the glass.

At the particle level? Freedom. No obligation to move forward.

I think about Ranchoddas Chanchad. The name itself is a joke, a pseudonym stolen from a servant’s son, worn by a kid who snuck into engineering college because he loved machines. Everything about him runs backward. The system says memorize first, understand later (maybe never). Rancho understands first. Joy first. The system says get the degree, then you have permission to learn. Rancho learns without permission and the degree chases him.

When his friend Farhan finally calls his father and says “I want to be a wildlife photographer,” that’s a reversal. Twenty-two years of moving forward through someone else’s expectations, and one phone call traces it all back to the source. What did you actually want, before anyone told you what to want?

Backpropagation works the same way.

Data flows forward: input to hidden layers to prediction. The prediction is wrong. It’s always wrong at first. The gap between prediction and truth is called loss.

Here’s the magic. The loss flows backward. Through every layer, every connection, every weight. Each parameter asks one question: how much of this error is mine? Then it adjusts. Millimeter by millimeter, the network rewires itself toward truth.

The forward pass is arrogant. It makes claims. The backward pass is honest. It traces error to its source.

When Raju stands on the ledge, Rancho reaches backward. He channels Raju’s paralyzed father, speaks as him, goes to the root. The suicide attempt is just the loss signal. The real error started years ago, in shame, in fear, compounding silently.

You fix a network by backpropagating. You trace the error home.

The Yoga Sutras call it pratyahara. Withdrawal. Tracing attention backward before it attached to objects, before it became craving. Following the gradient of suffering to find which ancient weight keeps producing the same pain.

Moksha, liberation, comes from muc, to release. Release from forward momentum. From the assumption that more accumulation will eventually equal peace.

It won’t. The function itself needs questioning.

Feynman’s electron bounces off the present and heads back. Rancho looks at a system designed to move students forward through fear and asks, what if we start with joy instead? A neural network makes a wrong prediction and the error travels home, finds every weight that contributed, asks each one to change.

We accumulate so much. Degrees, identities, fears we’ve learned to call wisdom. Layer after layer until the original signal is buried. The child who was curious before anyone told them what curiosity was for. The kid who loved cameras and engines before learning they belonged to separate careers.

When Farhan’s father finally says “live your life,” we cry because a gradient reached all the way back. Twenty-two years of accumulated error, finally acknowledged. By reversing.

Rancho disappeared at the end of the film. They found him years later, in Ladakh, teaching children, having built a school, having won the Padma Shri without ever chasing it. He was living at the source. He’d been there all along.

The positron knew all along: you can always turn around.

Too much to unlearn. Only one life. The backward path is shorter than it seems.